Ralzemond d



R. D. PARKER. SECRET SIGNALING SYSTEM.

APPLICATION FILED SEPT-13.1918.

Patented Aug. 12, 1919.

INVENTOR. RDPaI-"ker BY 5. W

A TTORNE Y RALZEMOND D. PARKER, OF BROOKLYN, NEW YORK, ASSIGNOR T0 AMERICAN TELE- PHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

SECRET-SIGNALING SYSTEM.

*tain Improvements in Secret-Signaling Systems, of which the following is a specification.

This invention relates to signal transnntting systems and especially such as are designed to maintain secrecy in the transmission of messages. Efforts have been made to secure secrecy in telegraph transmission by disguising the signals or breaking up the message between different conductors so that unauthorized persons tapping the transmission wires would be unable to read the message. These for the most part are ineffective because the disguising of the message is insufiicient to prevent a skilled operator from deciphering it, or there is danger that the unauthorized person may secure access to all of the several wires used for the transmission of the message. It is the object of the present invention to provide a system in which these dangers are liminated, and in which economy and efiiciency are attained as compared with other secret systems by the use of but a single conductor.

The invention will be described in connection with the accompanying drawing which illustrates one embodiment thereof. In gen- .eral the invention may be said to comprise two synchronously operating devices at the opposite ends of a line for breaking up or disguising the signals at the sending end and restoring them at the receiving. end, and means operating over the message carrying circuit, for coordinating these devices.

In the drawing the main line is indicated at 1 and is provided at each end with arrangements for duplex operation, including ratio arms 2 and 3 connected at their junction to the sendin branches r and at and at their opposite ends to the main line and to artificial lines 5 and 5 respectively. The receiving branches at the opposite ends are connected between the main and artificial lines at their junction with the ratio arms as usual and include polarized relays 6 and 6'.

As shown in the drawing the message is designed to be sent from the left hand end of the circuit by operation of the relay 7 controllingthe switch 8; and the synchr Specification of Letters Patent.

Patented Aug. 12, 1919.

Application filed September 13, 1918. Serial No. 253,966.

nizing impulses for controlling the ciphering and deciphering devices are sent from the right hand end of the line by the operation of relay 9 controlling the switch 10. The message is sent from the key 11 in the ordinary Morse or any other desired code. This key controls the relay 12 whose armature 13 opens and closes the circuit of the relay 7 as usual, except when cooperating with the ciphering device 14 which is here provided for disguising the signals.

The device H comprises rotating switching mechanism similar to the distributer commonly used in ordinary printing telegraph systems. The drawing illustrates only the five segmental contacts of such a distributer necessary for the present invention these being indicated at 15, 16, 17, 18, 19. The inner continuous ring 20 is put into electrical contact with each of the five segments successively by the brush 21 on the rotating arm This arm is arrested at each revolution by the latch 23 until released by operation of the magnet 52*. Each of the segments 15, 1G, 17, 18, 19 is connected with one of five contacts 25, 26, 27, 28, 29, any desired ones of which may be moved to connect the corresponding segments to a source of current as desired. These contacts 25 to 29 are here illustrated as the contacts of the ordinary tape transmitter used for printing telegraphy, and are arranged to oscillate between bus-bars 30 and 31 under the control of a. perforated tape (not shown) stepped along with each revolution of the arm by means of a magnet in a manner well known in the art. The bus-bar 30 is connected to a source of current in the circuit of magnet 37.

For disguising the signals the armature 13 of the relay 12 is provided with both front and back contacts 32 and 33, connected respectively with the front and back contacts 34 and 35 of the armature 36 controlled by the magnet 37 which acts as a ciphering relay. The armature 36 is connected to the source of current 38 for operating the relay 7. By this arrangement it will be seen that the relay 7 will be energized only when the anmatures of relays l2 and 37 are both either upon the front contacts or upon the back contacts of the respective relays. If therefore it happens-that the Morse key 11 is closed when the magnet 37 is unenergized,

no impulse will be transmitted to the relay 7 because the circuit thereof will be open at the front contact 34 of said magnet. On the other hand when the key 11 is not closed an impulse may be transmitted over the line, if it happens that the relay 3? is also unenergized at the moment. The circuit of magnet 7 will then be completed through the back contacts 35 and 33 of the two relays 37 and 12. It will be obvious of course that front contact 82 might be connected to back contact '35 and back contact 33 to front contact 34 without changing the principle of op eration; the only difference being that to send an impulse over the line it would then be necessary for one relay to be ('leenergized while the other was energized instead of both being either energized or deinergized.

At the opposite end of the line the signal impulses will be received in the windings of the polarized relay 6 which will close the circuit of magnet 39 each time an impulse from the battery 38 energizes the magnet 7 at the sending end. The armature 40 of magnet 39 is in the local receiving circuit including the battery 41 and sounder 42. For the purpose of=restoring the received impulses to the form in which they were created at the key 11, the local circuit includes a second armature 43 controlled by magnet 44 energized through a switching mechanism 45 generally similar to the switching mechanism 14 at the sending end of the line. The armatures 40 and 43 in the local receiving circuit operate between front and back contacts 45-l7 and 4849 respectively as in the case of the armatures of magnets 12 and 37 at the sendingstation and interconnected in the same way. The switching mechanism 45 includes a distributer with five segments 46, 47, 48, 49, 50 serving, with the rotating arm 59, to connect the circuit of the magnet 4-4 successively with five different circuits running to the contacts 51,52, 53, 54, 55 of a tape transmitter or similar device as in the case of thesending station. The contacts oscillate, under the control of a perforated tape, between the bus-bars 56 and 57; the bus-bar 56 being connected to a source of current in the circuit of magnet 44.

Upon the same shaftGO, with the arm 59 is another rotating arm. 61 carrying an insulated brush 63 which passes over the segment 62 in a second distributer face, once for each revolution thereby connecting it to ground through the ring 64. The circuitof magnet 9 in the sending branchof the duplex set is thus energized once for each revolution of the shaft 60. The contact 6'2 may conveniently be one of the contacts of the usual distributor used in. connection with printing telegraphy. In the present instance the ring in which the contact 62 is mounted is arranged to be rotated about the shaft 60 independently of the segments 46 to This mechanism is indicated in the present instance by the latch 65 located to arrest the arm at each revolution, and the magnet 66 arranged to withdraw the latch. at the instant it arrests the arm. The circuit of the magnet may be-controlled through any of the moving parts of the distributer and is here shown as completed at the contact between the latch 65 and the arm 61 as the latter is arrested by the latch.

In the operation of the system the messages are transmitted from the key 11 in the usual Morse or other code, and the impulses are converted or broken up by the magnet 37 under the influence of the distributer 14 so as to be unintelligible. This distributor and that at the opposite end of the line may be running continuously or may be set in operation by any means known in the art, or in accordance with anyv prearrangement between the operators. For causing the contacts of the tape transmitters to change their arrangements for successive lettersor successive periods of time during the message, identical perforated tapes will be run through the transmitters at the opp0 site ends of the line. If the arrangements of contacts 25 to 29 were not altered at all, it will be obvious that the message impulses would be so changed that they would no longer read as transmitted from the key 11. If, however, the arrangements of these contacts is altered as above indicated at frequent intervals corresponding say approximately to the time required for transmitting a letter at the key 11, the result will be not only a ciphered message but a message in which the cipher is changed for every letter transmitted. If the tape used in the transmitter is designed to give a series of arrangements which do not repeat during the time that the line is in use, or repeat only at longintervals, it will be to all intents and purposes absolutely impossible to decipher the message by tapping the line and recording the impulses transmitted.

At the receiving end of the line the distributer 45 in connection with the tape transmitter provided as above stated with a controlling tape identieal with that used in the transmitting instrument, has its mot-ion time to energize the magnet 44 at the same instant that the impulse created by the operation of the magnet 37 at the sending end, arrives int-he magnet 39. The result will be that the disguised impulses received in the magnet 39 will be reformed in the local circuit by the cooperation of magnet 44, so that the impulses supplied to the sounder magnet 42 will be the same as those supplied to the magnet 12 at the sending end by the key 11. The distributer arms 59 and 61 are arranged to rotate continuously under the start-stop control of the latch 65 and magnet 66. The arm 22 at thesending end of the line is driven at a speed corresponding as nearly as may be'with the speed of the arms 59 and 61, and perfect synchronism is obtained by the start-stop control of the latch 23 and the magnet 24 of the sending distributer, the magnet 24 being energized by an impulse transmitted from the start contact 62 at the opposite end of the line. This impulse passing through the magnet 9 operates the switch 10 which sends an impulse dividing equally between the main and artificial lines, and hence ineffective in the magnet 6, but effective in the magnet 6 at the opposite end of the line, which controls the circuit of the start magnet 24. Hence the arm 22 will not start a new rotation until released bythe operation of the arm 61 at the opposite end of the line.

The message impulses from the sending end of the line will arrive in the receiving magnet 39 only after an appreciable length of time, and likewise the start impulse from the sending end will reach the release magnet at the sending end an appreciable length of time after it is sent from the receiving end. In order, therefore, that the magnet 44.- may operate in phase with the magnet 39 it will be necessary to have the start contact 62 angularly advanced with respect to the distributer 45 whereby the start impulse for the sending'distributer will be despatched over the line somewhat before the shaft 60 carrying the arm 59 of the receiving distribu ter is released by the latch 65. Thus the contact ,62 for sending the start impulse to magnet 24 is shown on the drawing as having been passed over by the arm 61, and arm 22 has been released and has started to rotate while the latch 65 is still retaining the arm 61.

This invention, it will be seen, provides a comparatively simple and very effective means for maintaining secrecy in the transmission of telegraph signals when transmitted by the Morse code or according to any other known system, and the object is accomplished with the use of only a single transmission circuit. It is to be understood that the invention is not limited to the precise system herein shown and described, as obviously various modifications may be made without departing from the spirit of the invention or the scope of the appended claims.

What is claimed is: I

1. In a signal transmitting system, amain line, sending apparatus at one end thereof,

receiving apparatus at the other end thereof, a ciphering device at the sending end for rendering the signals unintelligible, a deciphering device at the receiving end for reconverting the transmitted impulses into intelligible signals and means for sending impulses over the line for synchronizing the operation of said ciphering and deciphering devices, simultaneously with the transmission of the signal impulses.

2. In a signal transmitting system, a main line, sending apparatus at one end thereof, receiving apparatus at the other end thereof, a ciphering device at the sending end for rendering the signals unintelligible, a deciphering device at the receiving end for reconverting the transmitted impulses into intelligible signals, means for sending im pulses over the line for synchronizing the operation of said-ciphering and deciphering devices, simultaneously with the transmission of the signal impulses and means for adjusting the phase relation of the said devices to compensate for the time required to transmit the impulses.

3. In a signal transmitting system, a main line, sending apparatus at one end thereof, receiving apparatus at the other end thereof, a ciphering device at the sending end for rendering the transmitted signals unintelligible, a deciphering device at the receiving end 'for reconverting the transmitted impulses into intelligible signals and means at the receiving end for transmitting impulses to the sending end simultaneously with the transmission of the signal impulses, for synchronizing the ciphering and deciphering devices.

4. In a signal transmitting system, a main line, sending apparatus at one end thereof, receiving apparatus at the other end there of, a ciphering device at the sending end for rendering the transmitted signals unintelligible, a deciphering device at the receiving end for reconverting the transmitted impulses into intelligible signals, means at the receiving end for transmitting impulses to the sending end simultaneously with the transmission of the signal impulses, for synchronizing the ciphering and deciphering devices and means for adjusting the phase relation of the said devices to compensate for the time required to transmit the impulses.

5. In a signal transmitting system, a main line, a sending circuit at one end of the line including means for creating signal impulses, switching mechanism for breaking up said signal impulses to render them unintelligible before they reach the main line, a receiving circuit at the other end of the line including means adapted to cause impulses therein corresponding to those arriving over the line, a second switching mecha- -.nism for restoring the received impulses to their original form in said receiving circuit and means operating over said main line for coordinating the movements of said switching mechanism without interrupting the signal impulses.

6. In a signal transmitting system, a main line, a duplex set at each end of the line, means for transmitting signal impulses in one direction over said line, a ciphering device at the sending end, a deciphering device at the receiving end of said line and 10 means for transmitting impulses over the line in the opposite direction for coordinating the action of the ciphering and deciphering devices.

In testimony whereof, I have signed my 15 name to this specification this tenth day of September, 1918.

RALZEMOND D. PARKER. 

